L-Tyrosine
The direct precursor to dopamine, norepinephrine, and adrenaline. Shines under stress and sleep deprivation — restores cognitive performance when catecholamines are depleted.
Strong RCT evidence for cognitive performance under cold stress, sleep deprivation, sustained operations, and mental fatigue (Banderet & Lieberman foundational work). Useful as adjunct in mild ADHD and depressive symptoms with low catecholamine activity. Acute effects: 30–90 minutes.
L-Tyrosine is an amino acid the body converts (via L-DOPA) into dopamine, then noradrenaline, then adrenaline — the catecholamine neurotransmitters that drive focus, motivation, alertness, and stress response. Under acute stress or sleep deprivation, the brain burns through catecholamine precursors faster than it can replace them — that's when supplemental tyrosine shows the biggest effect. It's been studied extensively in military contexts (sustained operations, cold exposure) and consistently restores cognitive performance under those conditions. In a well-rested, low-stress state it does much less. Also a thyroid hormone precursor.
- Form
- L-Tyrosine (the standard amino acid). N-Acetyl L-Tyrosine (NALT) is marketed as more bioavailable but actually delivers less tyrosine to the brain — stick with plain L-Tyrosine.
- Dose
- 500–2,000 mg per dose, acute. Up to 150 mg/kg total in military / stress-research protocols. 500 mg is a comfortable starting point.
- Timing
- Empty stomach, 30–60 min before cognitive demand or stressful situation. Don't take with a protein meal — competes with other amino acids for brain transport.
- Schedule
- As-needed (acute use). Daily use is less well-supported and can deplete other amino acids over time. Best used pulsed.
- Side effects
- Generally well-tolerated acutely. Headache, GI upset, anxiety, irritability in some. Can raise blood pressure in sensitive individuals.
- Interactions
- MAO inhibitors — potentially serious hypertensive reaction (tyramine-like). Levodopa (Parkinson's) — competes for absorption. Thyroid hormone (tyrosine is a precursor; usually no clinical interaction at supplement doses). Stimulants — additive effects.
- Contraindications
- Hyperthyroidism (precursor to thyroid hormone). Pheochromocytoma (catecholamine-secreting tumor). On MAOIs. Bipolar disorder (manic phase). Pregnancy (limited data above food intake).
- Lab markers
- Not routinely tested. TSH if running daily for extended periods. Catecholamine panels in research only.
- Food sources
- High-protein foods: turkey, chicken, cheese, fish, beef, soy, almonds, sesame seeds, pumpkin seeds. Most omnivores get plenty from diet — the supplemental case is for acute / pulsed use under stress.
Pairs with
Caffeine + L-theanine — the classic 'focus stack' that adds tyrosine for cognitive demand. Vitamin B6 (P5P), folate (cofactors for catecholamine synthesis). Iron, copper (also catecholamine-pathway cofactors).
within Amino acids & derivatives